The present invention relates to a liquid crystal display (LCD) device, and more particularly, to a LCD panel for a LCD device.
A LCD panel is formed by an array substrate and a color filter substrate that are assembled together with liquid crystal material filled between the two substrates. During manufacturing of LCD panels, a distance between the array substrate and the color filter substrate, i.e., a cell gap, is an important parameter.
In order to maintain the cell gap between the array substrate and the color filter substrate consistent, spacers having a certain height are disposed between the two substrates before assembling the two substrates. The spacers typically used mainly include two kinds of spacers: ball spacers (BSs) and post spacers (PSs). With respect to LCD panels using ball spacers, the ball spacers are a component used individually in the manufacturing process and are dispersed onto the array substrate or the color filter substrate by a dispenser, and thus the cell gap is maintained consistent with the dimensional stability of ball spacers during the assembling procedure. However, when using the dispensing method, ball spacers may be dispensed onto pixel areas and the orientation of liquid crystal material around the ball spacers may be adversely affected, causing light leakage and decreasing contrast. If post spacers are used during manufacturing LCD panels, post spacers are disposed at the black matrix (BM) on color filter substrate (C/F) so as to control the cell gap and improve contrast. Also, light leakage in pixel areas, which may be caused by using ball spacers, can be prevented by precisely controlling the position of post spacers in each pixel area.
Post spacers include primary post spacers and secondary post spacers, when post spacers are used for manufacturing LCD panels. The primary post spacers and secondary post spacers are used in cooperation by many manufactures, and the post spacers are uniformly distributed over the whole color filter substrate. The primary post spacers are higher than the secondary post spacers, and the area of the bottom surface of each primary post spacer approximately equals to that of each secondary post spacer. The primary post spacers contact with the upper portion of the array substrate to control the cell gap, while in normal condition the secondary post spacers do not contact with the array substrate. As shown in FIG. 6, the periphery portion of a LCD panel is bonded together by sealant 9. Normally, the cell gap at all portions are consistent, that is, for example the cell gap “a1” equals to the cell gap “b1” in a central portion and a side portion in a normal condition before impact, respectively. However, if the left side of the panel is subject to compression or impact, as shown in FIG. 7, on one hand, the array substrate 2 deforms causing displacement between the array substrate 2 and the color filter substrate 1, as shown in portion S of FIG. 7, and on the other hand, cell gap changes due to the fluidity of liquid crystal materials, at which time, the cell gap “b2” at the light leakage portion after impact is greater than the cell gap “b1” before impact, which equals to the cell gap “a1,” and the cell gap “a1” at the compressed portion before impact is greater than the cell gap “a2” at the compressed portion after impact. Therefore, when the panel is subject to impact, the secondary post spacers 4 shift move onto a thin film transistor (TFT) device or a data line. Meanwhile, because of the high density of the secondary post spacers and the high friction force between secondary post spacers 4 and the TFT device or the data line, the color filter substrate cannot return to its original position quickly, causing light leakage. In the figure, the light leakage portion 6 is on the right side from the central portion of the color filter substrate, deteriorating the display quality.